Provided is a method for stably conducting a process for producing chlorosilanes by a chlorination reaction of metallic silicon. When producing chlorosilanes by the chlorination reaction of the metallic silicon, metallic silicon having a sodium content of 1 ppm or more and 90 ppm or less in terms of element and an aluminum content of 1000 ppm or more and 4000 ppm or less in terms of element is used as the metallic silicon. An average particle diameter of the metallic silicon is preferably about 150 m to 400 m.

The invention provides a method for the processing of finely divided solids during the production of chlorosilanes, which is characterized in that the finely divided solids are hydraulically pressed to give bodies of increased density. Moreover, also provided is the compact obtained by the process according to the invention which is characterized by a filling factor of the finely divided solids to be hydraulically pressed of 3.9 to 4.5.

Improved hydrochlorination reactors, which have a larger internal volume and hence functional capacity than presently available hydrochlorination reactors, may be prepared with reactor walls having inner and outer layers where each layer provides a unique benefit, the inner layer having hydrogen chloride resistance and the outer layer having high strength at elevated temperature and pressure. Alternatively, or additionally, hoops may be disposed along the outside of the reactor wall to provide additional strength to the reactor during operation. Specified materials may be used to form the reactor wall in order to provide both acid resistance and high strength at elevated operating temperatures.